Police say the woman and her 18-year-old daughter were horseback riding in the 3600 block of 34th Street at about 8:40 p.m. PT.
The woman was apparently tossed from her horse’s back when the animal was spooked by a dog.
The woman’s daughter tried to follow the first horse as it galloped away, but the teen was subsequently thrown from her own horse as it tried to jump a ditch.
The mother was taken to Vancouver General Hospital where she later died.
The daughter was taken to a local hospital, where she was treated for scrapes to her face and bruising on her leg.
The teen’s horse was pulled out of the ditch by firefighters, with the help of some farming equipment. The animal could be seen walking away from the scene.
The victim’s names have not been released.